静态函数会隐藏具有相同名称的非静态函数吗？

Question

I tried to look this up, but did not find it anywhere. So here's the question:

Static functions in C/C++ can be used to "make them invisible to the outer world". Great, when having two same-named static functions in two different compiled units (.c files), it makes me sure that I call the right one. But can I also be sure that I call my local static function when there exists a same-named non-static function somewhere in the project or libraries? That is, does the static function locally hide the non-static one?

Sure I can test it (and I did) but I want to know whether this behaviour has fixed definition in C/C++. Thanks.

Edit : Simplified example code which caused unexpected behaviour to me. The question is about the fix of the problem (suppose I cannot change the library).

In mylib.c:

#include "mylib.h"
int send(void * data, int size);
...
int send(void * data, int size) {
    return send_message(queueA, data, size);
}
void libfunc(void) {
    send(str, strlen(str));
}

In mylib.h:

// only libfunc is declared here
void libfunc(void);

In myprog.c:

#include "mylib.h"
int send(void * data, int size);
...
int send(void * data, int size) {
    return send_message(queueB, data, size);
}
void progfunc(void) {
    // expected to send a message to queueB
    // !!! but it was sent to queueA instead !!!
    send(str, strlen(str));
}

Compiled mylib.c + further files -> mylib.a

Compiled myprog.c -> myprog.o

Linked myprog.o + mylib.a -> myprog

Answer 1

You'd get a compilation error because functions have default external linkage, thus the new static function would result in a conflict of linkage specifiers.

If the declaration of the non- static function isn't visible, the static one will be called:

void foo();            //external linkage
static void foo() {};  //internal linkage and error

Answer 2

It does not hide functions with same name declared in the same scope. However you may not have a function with the same signature declared as having internal and external linkage.